1. Technical Field
The present disclosure relates to a gaze detector which detects a gaze direction of an object from a captured face image, in particular, relates to a technology which reduces effect caused by the difference between a head posture at a time of performing calibration and that in actual use after calibration.
2. Description of the Related Art
As a method for detecting a gaze direction, there is widely used a corneal reflection method in which infrared light is projected to an eye of a person to be measured and a gaze direction is detected from a positional relationship between a reflection image (called as a Purkinje image) of the infrared light formed on a cornea and a pupil center. However, detection of the gaze direction using an image is affected by personal difference in a shape or thickness of a cornea or the like or affected by outfits such as eyeglasses or contact lenses.
Depending on a shape or material of an outfit such as eyeglasses, the effects of refraction may vary at different angles. In such a case, every time a head posture changes, in other words, every time the outfit is equipped and removed, the state when calibration is performed varies; therefore, it is necessary to perform calibration every time the outfit is equipped and removed, and as a result, a person to be measured has to bear a heavy burden.
In a normal calibration process, a plurality of standard points need to be looked at when calibration is performed again; however, Unexamined Japanese Patent Publication No. 2001-134371 discloses a method in which only any one of the points needs to be looked at to estimate whole errors.